Tho objective of the project is to develop an accurate method for measuring blood flow using small, flat, disposable sensors that can be placed on or near the blood vessel. This new method of angle-independent Doppler velocity determination requires diffractive transducers, whose plane can be oriented parallel to the flow. Ultrasonic Doppler methods are now widely used in medicine for measuring and mapping blood flow. All high end ultrasonic scanners have Doppler and Doppler imaging capabilities. The problem with Doppler techniques is that the velocity extracted from Doppler shift is angle dependent and the angle is difficult to estimate. As a result, the error can be as large as 50%. This new method may offer a solution to this long standing problem. Diffractive transducers have been fabricated in the frequency range form 5 to 25 MHz range and used in conjunction with an instrument developed at Echocath for animal and patient studies. FEA simulation of transducer performance has also been carried out.